Resource requirements, behaviour, and weather constraints on activity of the butterfly Aporia crataegi in Normandy, France

The Black-veined white butterfly ( Aporia crataegi ) is a widespread Palearctic species facing substantial declines across its European range. This species became extinct in the British Isles in the 1920s. However, the projected drying climate in south-eastern Britain could provide suitable conditions for a reintroduction attempt.The aim of this study is to identify the resource requirements of adult A. crataegi , including egg-laying, feeding, roosting, and mating, and to collate information on individual longevity and mobility. We also investigate how environmental resources and weather affect adult activity. We found that A. crataegi used a variety of nectar resources but had a distinct preference for the flower colour purple. Females laid eggs mainly on small plants of Prunus spinosa and Crataegus monogyna and significantly preferred isolated host plants or those in defunct and gappy hedgerows. Aporia crataegi was positively associated with the percentage of host and nectar plants and showed a positive relationship with a heterogeneous distribution of host resources, a homogeneous distribution of nectar resources, and much spatial overlap of these resources. Air temperature, solar radiation intensity, and windspeed affected the activity of both sexes. Under cloudy conditions, sexes were active at different temperatures with females needing higher temperatures and solar radiation than males to become active. Implications for insect conservation Our results provide fine-scale microhabitat and climatic requirements of A. crataegi including oviposition sites, resource composition, organisation and distribution requirements, which are key to supporting evidence-based conservation strategies within this species current range, as well as in support of a reintroduction attempt.